From what you say you want..ability to cook low and slow and also grill at 700 degrees, I think the Yoder would be your best bet if you get the two piece diffuser and grill grates. The Yoder setup like this is great. Cookshack makes some decent rigs as well, but capacity is limited as a smoker on them. Mak is another good choice, but as you noted, it costs a fair bit more.
The Pitts and Spitts excels as a low and slow smoker, and while it can function as a grill, it is limited in this aspect.
I think the Yoder makes the most sense for you, and since you already have an offset, you can still do the stick burning thing for when you want that taste, and use the pellet for busier times. Good luck.
